World 6-7 (Super Mario Bros. 3)
From the Super Mario Wiki
World 6-7 is the seventh main level and the eighth level overall of Ice Land in Super Mario Bros. 3. It becomes accessible after the player has cleared World 6-5 or World 6-6 and its own completion unlocks World 6-Fortress 2.
This level is an autoscroll level which is comprised of Donut Lifts that will begin to fall once the player steps on them for a bit. They will also have to cross while making it past Fire Chomps. The Donut Lifts allow descending them for coins below, but the player must be careful to jump to the next platform after descending or else he or she will fall into the pit. At the end, it is required to make the final Donut Lift on the ice platform fall down a little so the player can jump to the two Jump Blocks next to the pipe. They can go down the pipe and find a Koopa Troopa in between a structure of frozen coins. The Fire Flower may then be used to shoot fireballs at the ice and grab the coins that were part of the structure. There is also a hidden coin block to the left of it to allow the player to reach the platform if they fall down to that side. To the right, the player will find the goal.